Pit and Fissure Sealants in High-Risk Individuals

In 1983 the National Institutes of Health hosted a consensus development conference on dental sealants in the prevention of tooth decay (NIH, 1984). The panel�s conclusion was that the "placement of sealants is a highly effective means of preventing pit and fissure caries." The panel said that sealants were 100 percent effective in pits and fissures that remained completely sealed, although sealant retention declines over time. Since then, there have been comprehensive reviews (Weintraub, 1989; Ripa, 1985, 1993) and a meta-analysis (Llodra, Bravo, Delgado-Rodriguez, et al., 1993) that confirmed the effectiveness of sealants and a workshop that developed guidelines for their use (Siegal, Kumar, 1995). Sealants are still needed, since 78 percent of 17-year-olds in the United States have experienced dental caries (Surgeon General, 2000), and most of the disease occurs in pits and fissures (Kaste, Selwitz, Oldakowski, et al., 1996). Sealants, however, are far from being universally applied. In 1988-94, only 23 percent of U.S. 8-year-old children and 15 percent of 14-year-old children had received sealants (U.S. DHHS, Healthy People 2010). The current charge is to examine the evidence demonstrating the effectiveness of sealants in high risk children and to discuss the findings of the Research Triangle Institute/University of North Carolina group.

The RTI/UNC group used four initial criteria to select caries management studies: (1) studies of methods applied or prescribed in a professional setting (or professional provision); (2) in vivo studies; (3) studies with a concurrent comparison group; and (4) studies using traditional outcome measures of caries experience. For studies of the management of noncavitated lesions they included studies where the lesion was the unit of analysis. For studies on the management of caries in high-risk individuals, the risk determination was "made on an individual subject level based on carious lesion experience and/or bacteriologic testing." In other words, high-risk status conferred by group membership, such as a school or community with a high caries rate or low socioeconomic status, was not sufficient.

Because of these restrictive criteria, the investigators found only one study (Heller, 1995) that met the criteria and examined sealant use in noncavitated lesions, and only two studies that met the criteria and used sealants alone (Sheykholeslam, Houpt, 1978) or sealants in combination with other preventive agents in high-risk individuals (Zickert, Emilson, Krasse, 1982). Another sealant study was listed in the references but is not found in the tables (Carlsson, Petersson, Twetman, 1997).

This presentation will describe the RTI/UNC criteria, as well as those four studies and their limitations, in more detail. Additional studies are also discussed to better reflect the nature of sealant studies and include the studies that appear in this abstract�s tables 1 and 2.

Many of the first trials of sealants used a half-mouth design where children with one or two pairs of sound, homologous molars were included. Sealant was applied to one randomly selected molar while its pair was left unsealed. Most of those trials did not specifically discuss caries risk status, but review indicates that some of them specifically selected children with prior caries experience (Buonocore, 1970, 1971; Brooks, Mertz-Fairhurst, Della-Giustina, et al., 1976; Mertz-Fairhurst, Fairhurst, Williams, et al., 1984; Sheykholeslam, Houpt, 1978; Houpt, Shey, 1983; McCune, Bojannini, Abodeely, et al., 1979), either in general or specifically first permanent molars. In the latter case, studies such as those by Rock, Gordon, and Bradnock (1978) and Rock and Evans (1982) required all four first permanent molars to be erupted and caries-free in 6-7 and 8-year-olds, respectively. Thus, these children might have been at lower caries risk than children who did not have all four molars caries-free (McCune, Horowitz, Heifetz, et al., 1973; Weintraub, Stearns, Burt, et al., 1993.)

Other studies with a half-mouth design included children with one or two pairs of sound, homologous, first permanent molars. The proportion of children contributing only one pair may be indicative of at least one member of the other pair being unerupted or (more likely) carious, depending on the age of the child. The proportions of pairs of caries-free teeth available may have been a surrogate measure of the child�s caries status, indirectly correlated with caries experience and caries risk. These studies likely included a mix of low- and high-risk children. The current effectiveness of sealants is underestimated because the first generation of material used, polymerized by ultraviolet light, was less effective than newer materials and is no longer in use (Ripa, 1993). The retention rate in any sealant trial is also dependent on the accuracy with which examiners can identify the presence of sealant. Misclassification occurs more often when a clear resin rather than an opaque resin is used (Rock, Potts, Marchment, et al., 1989).

Caries risk can be considered at the personal level or at the tooth level. Some studies have compared sealants on carious vs. noncarious teeth (Leverett, Brenner, Handelman, et al., 1983), or on sound surfaces vs. surfaces with incipient lesions (Heller, Reed, Bruner, et al., 1995). In 1991, Handelman reviewed radiographic and bacteriologic studies investigating the therapeutic use of sealants and concluded that "caries is inhibited and may in fact regress under intact sealants." Some (Weerheijm, Groenn, Bast, et al., 1992) have expressed concern about occlusal radiolucencies beneath sealed surfaces. In retrospective sealant studies, dentists may or may not have selected high-risk children for sealant placement, but sealed and unsealed teeth can be compared in children, based on their prior caries experience as a measure of their caries risk status (Weintraub, Stearns, Rozier, et al., In press.) Recent attempts to target high-risk children have compared sealant survival rates (Kumar, Cavila, Green, et al., 1997), caries reduction (Carlsson, Petersson, Twetman, et al., 1997), or reduction of S. mutans levels (Mass, Eli, Lev-Dor-Samovici, et al., 1999) in teeth sealed in high-risk children compared to unsealed or sealed teeth in low-risk children.

Low risk —sealants effective up to 4 years, middle risk — lower odds for 6 years; high risk — reductions up to 7 years

Medicaid expenditure savings for high-risk children within 2 years; not for low risk.

Conclusions

Sealants are very effective if completely retained on the tooth surface.

Most sealant studies have included low-risk children (all four first molars caries-free), high-risk children (prior caries experience), or a mixture of both low- and high-risk children. However, analyses may not have been stratified by caries risk status. Sealants have been effective to varying degrees in all of these studies.

There is evidence that sealants are more effective in preventing further caries and providing cost savings in a shorter time span if placed in individuals (or teeth) with high caries risk compared to individuals with low caries risk.

Most caries risk assessment methods used in these studies relied on past caries experience or presence of incipient lesions. Caries risk assessment methods are needed to predict high risk prior to clinical caries development so that sealants can be used to prevent caries on all susceptible teeth.

Horowitz HS, Heifetz SB, Poulsen S. An overview of results after four years in Kalispell, Montana. J Prev Dent 1976;3:38�49.

Horowitz HS, Heifetz SB, Poulsen S. Retention and effectiveness of a single application of an adhesive sealant in preventing occlusal caries: final report after five years of a study in Kalispell, Montana. J Am Dent Assoc 1977;95:1133�9.

U. S. Department of Health and Human Services. Healthy People 2010. Available on the Web site: http://www.health.gov/healthypeople/document/html/volume2/21oral.htm#_Toc489700409

U.S. Department of Health and Human Services. Oral Health in America: A report of the Surgeon General. Rockville, MD: U.S. Department of Health and Human Services, National Institute of Dental and Craniofacial Research, National Institutes of Health, 2000.